Rotary switch and indexing means therefor



Sept. 9, 1969 J. H. M. WILL 3,456,407

ROTARY SWITCH AND INDEXING MEANS THEREFOR Filed Jan. 5, 1967 5 Sheets-Sheet 1 m l -L :m g I" 29 Li; H

. Mu 7- M INVENTOR S W-i 4% (9m X ATTORNEY Sept. 9, 1969. J. H. M. w||

ROTARY SWITCH AND INDEXING MEANS THEREFOR 5 Sheets-Sheet 2 Filed Jan. 5, 1967 INVENTOR BY M 5m ATTORNEY Sept. 9, 1969 J- H. M. WILL 3,466,407

ROTARY SWITCH AND INDEXING MEANS THEREFOR Filed Jan. 5, 1967 5 Sheets-Sheet 3 INVENTOR fizilwmm ATTORNEY Sept. 9, 1969 J. H. M. w|| 3,466,407

ROTARY SWITCH AND INDEXING MEANS THEREFOR Filed Jan. 5, 1967 5 Sheets-Sheet 4.

XJLmRW ATTORNEY Sept. '9, 1969 J. H. M. WILL 3,466,407

ROTARY SWITCH AND INDEXING MEANS THEREFOR Filed Jan. 5, 1967 5 Sheets-Sheet 5 W A i- 6 iNVENTOR XZLMCQM ATTORNEY United States Patent 3,466,407 ROTARY SWITCH AND INDEXING MEANS THEREFOR James Hector MacDonald Will, Farnborough, England, assignor to Datel Limited Filed Jan. 5, 1967, Ser. No. 607,408 Claims priority, application Great Britain, Jan. 6, 1966, 625/66 Int. Cl. H01h 19/58, 21/78 US. Cl. 20011 4 Claims ABSTRACT OF THE DISCLOSURE The versatility and adaptability of a rotary switch is increased by providing it with an index mechanism having at least two available sets of indexed positions. This is achieved, for example, by providing an index plate with two (or more) circular rows of recesses each row having a different number of recesses, and spring loaded balls engageable in any one of the rows, as selected. The operating range is further increased by having at least one rotor driven separately from the others through a reduction gearing, and again by providing an optional double revolution stop arrangement which permits the rotor to rotate through more than 360 but stops it positively before the end of a second revolution.

There is also described a controller unit, suitable for airborne navigation or communications systems in which a rotary switch is coupled to a film transport mechanism forming part of a display unit, so that a different part of the film, carrying, for example, information about the setting of the switch (such as the frequency selected), is displayed at each setting of the switch.

This invention relates to rotary action electric switches, for use, for example, as frequency selector switches for airborne navigation and communications systems and the like.

Rotary action switches usually comprise a rotor shaft carrying one or more rotors for co-operation with stationarily mounted contact means and an indexing mechanism for determining the number of switched positions of the rotor shaft.

The present invention provides a rotary action switch having a new and improved form of indexing mechanism which increases the versatility and useful range of applications of the switch.

In accordance with the invention, the indexing mechanism of such a switch has more than one set of index position determining means, either (or any one) of which sets can be selected for use in preference to the other (or any other).

The desired set of index position determining means can be selected for use on final assembly of the switch, so that switches having different numbers of indexed positions can be assembled from standard components, or, seen from another point of view, a switch could be adjusted during its operational life to alter the number of available indexed positions.

In a particularly useful application, the switch is incorporated in an airborne controller for navigation or communications system.

One form of switch in accordance with the invention is described below, by way of example only, with reference to the accompanying drawings, which show the 3,466,407 Patented Sept. 9, 1969 switch and an airborne controller with which it may be used.

In the drawings:

FIGURE 1 is a sectional elevation;

FIGURE 2 is a plan view (with some parts omitted for clarity) of a digital display unit forming part of the controller;

FIGURE 3 is a plan view, partly in section, of a combined digital display unit and rotary switch in accordance with the invention;

FIGURE 4 is a sectional elevation of a rotary switch in accordance with the invention;

FIGURES 5, 5A and 6 illustrate two typical stators of the switch of FIGURE 4;

FIGURES 7 and 7A illustrate a typical rotor; and

FIGURES 8 and 8A are a section and part section, respectively, on the lines B-B and DD of FIGURE 4.

The digital display unit shown in FIGURES 1 and 2 comprises a U-shaped housing 1, the side limbs of which rotatably support the shafts of two, side-by-side, reversible film transport mechanisms, each of which has two bobbins geared together by gear wheels 2 and 3. The film is guided from one bobbin to the other by guide shaft 4 (preferably of P.T.F.E. to reduce friction) and sprocket 6 past a lamp housing 7 containing miniature filament lamps. The ends of the films are held in the bobbins by U-shaped springs 8, preferably of beryllium copper locating in machined slots in the bobbins. Each film transport mechanism is separately driven by means of a drive shaft 9 carrying a gear wheel 11 meshing with a wheel fast with the sprocket 6. Indexing of the films is achieved by means of indexes 12, preferably of nylon, co-operating with spring loaded balls 13. One of the films may carry numerals representing hundreds, tens and units, While the other carries decimals. A suitable material for the film will be a polyester base matted on one or both surfaces. The numerals are preferably silk-screen printed onto the film, using vinyl based inks, preferebaly white on a black background.

Such a device can be provided as a unit for incorporation in apparatus, such as a frequency selection instrument, which requires a digital display indicating the setting of an adjustable rotary member. The characters printed on the films will of course be specially designed to fulfill a specified duty.

FIGURE 3 shows in plan view and with parts omitted for clarity a unit generally similar to that described above incorporated with a rotary switching mechanism'which may constitute a frequency selector.

The main shaft 21 of the mechanism carries a plurality of wafer-type rotors 22, which co-operate through suitable contacts with stators 23. An index mechanism 24 facilitates selection of any chosen one of a number, say 20 or 40, of different circuits by rotation of the main shaft. The arrangement and construction of the switching mechanism is generally the same as that of the mechanism described below in relation to FIGURES 4 to 8 of the drawings. In order that the digital display unit will be driven in synchronism, the main shaft carries a crown Wheel 26 meshing with a pinion 27, the shaft of which also carries a gear wheel 28 meshing with a pinion 29 carried by an extension of the drive shaft 9 of the display unit. This extension is preferably connected to the shaft 9 by means of a releasable coupling (not shown) positioned outside the housing 1 to facilitate disconnection of the unit from the remainder of the instrument.

A presently preferred form of rotary switch in accordance with the invention is illustrated in FIGURES 4 to 8. Mounted on the main shaft 21 are two rotors 22 which are mounted for rotation with the shaft, and which co-operate with stators 23 which are secured to the frame of the switch. Two typical stator wafers are illustrated in FIGURES and 6. The wafers are preferably of grade 1 S.R:B.P. or glass fabric laminate casing on which are printed by the printed board flush bonding technique rhodium plated contact areas. This type of stator levels itself to great flexibility of design for different requirements in that the take-off connections could be grouped, as illustrated, or positioned radially if desired. FIGURE 5A, which illustrates a typical take-off connection, is a part section of EE of FIGURE 5. Both of the stators illustrated have twenty different contact positions, although more or less positions could obviously be provided if desired. In the stator shown in FIGURE 5, there are essentially two concentric tracks, and in that of FIGURE 6 there are three.

A typical rotor is shown in FIGURE 7, and comprises a disc, preferably of nylon, formed with two concentric rows of apertures which permit the mounting of contact clips 31, of which two typical examples are illustrated in FIGURE 7A, which is a part section on the line CC of FIGURE 7, illustrates the mounting of two such clips. The clips may be of 625 gold alloy, up to ten clips may be mounted on one rotor.

A third rotor 32, which co-operates with a third stator 33, is rotatably mounted on the main shaft 21, from which it is driven by a 2:1 reduction gearing 36, 38, 38, 39, so that this rotor will be driven at half the velocity of the shaft 21, thus enabling twice the number of contact positions to be selected on the stator 33, if required.

The index mechanism 24 comprises an index plate 41 fast with the frame of the switch, and having two rows of index position determining recesses 42, 43 for co-operation with balls 44 mounted in radially elongated recesses 46 in a drive plate 47. The halls are urged towards the index plate 41 by annular leaf springs 48, 49. The plate 41 is preferably nylon faced to reduce friction. The spring 48 is operative when the balls are engaged in the outer row of recesses 43, of which there are twenty, and the spring 49 is operative when the balls engage in the ten recesses 42 of the inner row. Thus, the shaft 21 may have ten or twenty indexed positions, as desired in one revolution. A single revolution stop bar 51 is releasably secured to the drive plate 47, for co-operation with a stop pin 52 removably inserted in one of twenty apertures 53 in the index plate 41.

If desired, for a particular requirement however the stop bar 51 may be removed, and a double revolution stop device brought into effect. This device includes a rotary stop plate 54 which is rotatably mounted on the main shaft 21 and having a co-operating abutment or stop 56 for co-operation on the one hand with a radial pin or abutment 57 secured to a disc 58 mounted for rotation with the shaft 21, and on the other hand with a fixed stop pin 59 projecting from the index plate 41.

Assuming that the balls 44 are engaged in the outer row of recesses 43, and that the parts are in the extreme position illustrated in full line in FIGURE 8A, the operation of the double stop device is as follows. As the main shaft 21 is rotated, the disc 58 and radial pin 57 will rotate anti-clockwise as viewed in FIGURE 8A; almost at the end of the first revolution, the pin 57 will engage the stop 56, and during the next revolution the stop 56 will be carried round with the pin 57, until, towards the end of the second revolution, the stop 56 will encounter the fixed stop 59. Thus, the shaft 21 will have rotated through 702 with forty indexed positions equispaced at 18 of arc. If the inner row of recesses 42 is employed, a stop pin 59' is inserted where indicated in FIGURE 8A, and the main shaft will be rotatable through 684 with twenty indexed positions equispaced at 36 of arc.

The rotatary switch will thus be seen to be able to meet widely varying operational requirements, and is particularly well suited for use as a frequency selector for airborne communication and navigational systems. A digital display unit and frequency selector switch in accordance with the invention may be incorporated in a controller box for a communications or navigations system, or a single controller box may incorporate respective rotary switches and digital display units in acordance with the invention. Obviously, more than two sets of index position determining means could be provided if desired.

Many variations and modifications will be possible within the scope of the invention.

One possible modification consists in mounting one of the two film bobbins rotatably upon its supporting shaft and providing a spiral torsion spring having one end anchored to the bobbin and the other to the adjacent gear 2. This arrangement maintains the film sufficiently taut, while allowing for differential rotation of the two bobbins due to differences in the outside diameters of the coils of film thereon.

Another minor modification consists in firming the individual contacts 31 with three fingers instead of two in order to give greater assurance that good contact Will be made by at least one of them.

I claim:

1. Rotary switch means, comprising (a) a frame;

(b) stator means connected with said frame and including a set of fixed contacts;

(c) rotor means including a shaft journalled in said frame, said rotor means having rotor contacts arranged for cooperation with said fixed contacts; and

(d) indexing means for indexing the position of said rotor means relative to said stator means, said indexing means including (1) plate means having a planar surface normal to said shaft and containing at least two radially separated sets of index-position-defini-ng recesses, the recess sets having different numbers of recesses and being arranged in successive circles concentric with the shaft; and

(2) index-p0sition-determining means arranged for cooperation with said recesses to establish a given angular position of the rotor means relative to said stator means, one of said plate and said index-position-determining means being connected with said frame, and the other being connected with said shaft, said index-position-determining means including at least one spring-biased ball movable radially of said shaft into register with any selected concentric recess set, whereby selection of different sets of index position defining recesses for cooperation with said spring-biased ball affords the selection of a different number of indexed switch positions.

2. Apparatus as defined in claim 1, wherein said plate means comprises a stationary circular disc connected with said frame and having a central opening rotatably receiving said shaft,

3. Apparatus as defined in claim 2, and further including additional rotor means rotatably connected with said frame, and reduction gearing means coupling said additional rotor means with said shaft.

4. Apparatus as defined in claim 2, and further including means defining a limited range of rotational movement of said rotor shaft in excess of one revolution, comprising a first abutment (57) connected for rotation with said rotor shaft, a second abutment (56) rotatably mounted on said shaft for engagement by said first abutment, a stationary stop (59) fixed to said frame for engagement only by said second abutment, whereby during the first revolution of the rotor the first abutment is caused to engage and rotatably drive the second abutment, and

during the second revolution of the rotor the second abutment is driven toward the stationary stop.

References Cited UNITED STATES PATENTS Asbury 7410.5 X Serge 7410.8 X Schonstedt 74-527 Patla 74-527 6 2,931,333 4/ 1960 Whittier. 2,982,824 5/ 1961 Forrest. 3,316,770 5/1967 Badger et a1. 7410.8 X

ROBERT K. SCHAEFER, Primary Examiner D. SMITH, JR., Assistant Examiner US. Cl. X.R. 

